As processes for producing a phosphorescent body as described above, there have been known such conventional processes as described in Patent Documents 1 to 3, for example. In Patent Document 1, a glass tube having a hollow filled with phosphorescent powder is stretched to give fibrous glass, and the fibrous glass is put into an inclined heating furnace and melted at a temperature equal to or higher than its melting point, and thereby glass spherules are produced by the action of the surface tension. In Patent Document 2, phosphorescent cullet is sintered by fluidized sintering to produce glass beads. In both the production processes, the apparatus used was complicated and large-scaled, and the production steps were also complicated.
In Patent Document 3, a mixture of a phosphorescent material and a glass material is sintered to give plate-like glass, and the plate-like glass is pulverized to have a predetermined particle diameter and sintered again to form particles each including a light-emitting portion. Therefore, the production efficiency of the particles each including the light-emitting portion was low, and the production steps were still complicated. In some cases, in addition, the shapes of the particles were non-uniform.